﻿using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;

namespace Assets {
    /**
 * Utilities for encoding and decoding the Base64 representation of
 * binary data.  See RFCs <a
 * href="http://www.ietf.org/rfc/rfc2045.txt">2045</a> and <a
 * href="http://www.ietf.org/rfc/rfc3548.txt">3548</a>.
 */
    public class Base64 {
        /**
         * Default values for encoder/decoder flags.
         */
        public static  int DEFAULT = 0;

        /**
         * Encoder flag bit to omit the padding '=' characters at the end
         * of the output (if any).
         */
        public static  int NO_PADDING = 1;

        /**
         * Encoder flag bit to omit all line terminators (i.e., the output
         * will be on one long line).
         */
        public static  int NO_WRAP = 2;

        /**
         * Encoder flag bit to indicate lines should be terminated with a
         * CRLF pair instead of just an LF.  Has no effect if {@code
         * NO_WRAP} is specified as well.
         */
        public static  int CRLF = 4;

        /**
         * Encoder/decoder flag bit to indicate using the "URL and
         * filename safe" variant of Base64 (see RFC 3548 section 4) where
         * {@code -} and {@code _} are used in place of {@code +} and
         * {@code /}.
         */
        public static  int URL_SAFE = 8;

        /**
         * Flag to pass to {@link Base64OutputStream} to indicate that it
         * should not close the output stream it is wrapping when it
         * itself is closed.
         */
        public static  int NO_CLOSE = 16;

        //  --------------------------------------------------------
        //  shared code
        //  --------------------------------------------------------

        /* package */
          class Coder {
            public byte[] output;
            public int op;

            /**
             * Encode/decode another block of input data.  this.output is
             * provided by the caller, and must be big enough to hold all
             * the coded data.  On exit, this.opwill be set to the length
             * of the coded data.
             *
             * @param finish true if this is the   call to process for
             *        this object.  Will  ize the coder state and
             *        include any   bytes in the output.
             *
             * @return true if the input so far is good; false if some
             *         error has been detected in the input stream..
             */
            public  bool process(byte[] input, int offset, int len, bool finish) {
            return false;}

            /**
             * @return the maximum number of bytes a call to process()
             * could produce for the given number of input bytes.  This may
             * be an overestimate.
             */
            public  int maxOutputSize(int len) { return 0;}
        }

        //  --------------------------------------------------------
        //  decoding
        //  --------------------------------------------------------

        /**
         * Decode the Base64-encoded data in input and return the data in
         * a new byte array.
         *
         * <p>The padding '=' characters at the end are considered optional, but
         * if any are present, there must be the correct number of them.
         *
         * @param str    the input String to decode, which is converted to
         *               bytes using the default charset
         * @param flags  controls certain features of the decoded output.
         *               Pass {@code DEFAULT} to decode standard Base64.
         *
         * @throws IllegalArgumentException if the input contains
         * incorrect padding
         */
        public static byte[] decode(String str, int flags) {
            return decode(Encoding.Default.GetBytes(str), flags);
        }

        /**
         * Decode the Base64-encoded data in input and return the data in
         * a new byte array.
         *
         * <p>The padding '=' characters at the end are considered optional, but
         * if any are present, there must be the correct number of them.
         *
         * @param input the input array to decode
         * @param flags  controls certain features of the decoded output.
         *               Pass {@code DEFAULT} to decode standard Base64.
         *
         * @throws IllegalArgumentException if the input contains
         * incorrect padding
         */
        public static byte[] decode(byte[] input, int flags) {
            return decode(input, 0, input.Length, flags);
        }

        /**
         * Decode the Base64-encoded data in input and return the data in
         * a new byte array.
         *
         * <p>The padding '=' characters at the end are considered optional, but
         * if any are present, there must be the correct number of them.
         *
         * @param input  the data to decode
         * @param offset the position within the input array at which to start
         * @param len    the number of bytes of input to decode
         * @param flags  controls certain features of the decoded output.
         *               Pass {@code DEFAULT} to decode standard Base64.
         *
         * @throws IllegalArgumentException if the input contains
         * incorrect padding
         */
        public static byte[] decode(byte[] input, int offset, int len, int flags) {
            // Allocate space for the most data the input could represent.
            // (It could contain less if it contains whitespace, etc.)
            Decoder decoder = new Decoder(flags, new byte[len * 3 / 4]);

            if(!decoder.process(input, offset, len, true)) {
                throw new Exception("bad base-64");
            }

            // Maybe we got lucky and allocated exactly enough output space.
            if(decoder.op == decoder.output.Length) {
                return decoder.output;
            }

            // Need to shorten the array, so allocate a new one of the
            // right size and copy.
            byte[] temp = new byte[decoder.op];
            Array.Copy(decoder.output, temp, decoder.op);
            //System.arraycopy(decoder.output, 0, temp, 0, decoder.op);
            return temp;
        }

        /* package */
        class Decoder {
            public byte[] output;
            public int op;
            /**
             * Lookup table for turning bytes into their position in the
             * Base64 alphabet.
             */
            private static  int[] DECODE = {
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
            52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
            -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
            15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
            -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
            41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        };

        /**
         * Decode lookup table for the "web safe" variant (RFC 3548
         * sec. 4) where - and _ replace + and /.
         */
        private static  int[] DECODE_WEBSAFE = {
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1,
            52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
            -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
            15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63,
            -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
            41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
            -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        };

        /** Non-data values in the DECODE arrays. */
        private static   int SKIP = -1;
        private static   int EQUALS = -2;

        /**
         * States 0-3 are reading through the next input tuple.
         * State 4 is having read one '=' and expecting exactly
         * one more.
         * State 5 is expecting no more data or padding characters
         * in the input.
         * State 6 is the error state; an error has been detected
         * in the input and no future input can "fix" it.
         */
        private int state;   // state number (0 to 6)
        private int value;

          private int[] alphabet;

        public Decoder(int flags, byte[] output) {
            this.output = output;

            alphabet = ((flags & URL_SAFE) == 0) ? DECODE : DECODE_WEBSAFE;
            state = 0;
            value = 0;
        }

        /**
         * @return an overestimate for the number of bytes {@code
         * len} bytes could decode to.
         */
        public int maxOutputSize(int len) {
            return len * 3 / 4 + 10;
        }

        /**
         * Decode another block of input data.
         *
         * @return true if the state machine is still healthy.  false if
         *         bad base-64 data has been detected in the input stream.
         */
        public bool process(byte[] input, int offset, int len, bool finish) {
            if(this.state == 6) return false;

            int p = offset;
            len += offset;

            // Using local variables makes the decoder about 12%
            // faster than if we manipulate the member variables in
            // the loop.  (Even alphabet makes a measurable
            // difference, which is somewhat surprising to me since
            // the member variable is  .)
            int state = this.state;
            int value = this.value;
            int op = 0;
              byte[] output = this.output;
              int[] alphabet = this.alphabet;

            while(p < len) {
                // Try the fast path:  we're starting a new tuple and the
                // next four bytes of the input stream are all data
                // bytes.  This corresponds to going through states
                // 0-1-2-3-0.  We expect to use this method for most of
                // the data.
                //
                // If any of the next four bytes of input are non-data
                // (whitespace, etc.), value will end up negative.  (All
                // the non-data values in decode are small negative
                // numbers, so shifting any of them up and or'ing them
                // together will result in a value with its top bit set.)
                //
                // You can remove this whole block and the output should
                // be the same, just slower.
                if(state == 0) {
                    while(p + 4 <= len &&
                           (value = ((alphabet[input[p] & 0xff] << 18) |
                                     (alphabet[input[p + 1] & 0xff] << 12) |
                                     (alphabet[input[p + 2] & 0xff] << 6) |
                                     (alphabet[input[p + 3] & 0xff]))) >= 0) {
                        output[op + 2] = (byte)value;
                        output[op + 1] = (byte)(value >> 8);
                        output[op] = (byte)(value >> 16);
                        op += 3;
                        p += 4;
                    }
                    if(p >= len) break;
                }

                // The fast path isn't available -- either we've read a
                // partial tuple, or the next four input bytes aren't all
                // data, or whatever.  Fall back to the slower state
                // machine implementation.

                int d = alphabet[input[p++] & 0xff];

                switch(state) {
                    case 0:
                        if(d >= 0) {
                            value = d;
                            ++state;
                        } else if(d != SKIP) {
                            this.state = 6;
                            return false;
                        }
                        break;

                    case 1:
                        if(d >= 0) {
                            value = (value << 6) | d;
                            ++state;
                        } else if(d != SKIP) {
                            this.state = 6;
                            return false;
                        }
                        break;

                    case 2:
                        if(d >= 0) {
                            value = (value << 6) | d;
                            ++state;
                        } else if(d == EQUALS) {
                            // Emit the last (partial) output tuple;
                            // expect exactly one more padding character.
                            output[op++] = (byte)(value >> 4);
                            state = 4;
                        } else if(d != SKIP) {
                            this.state = 6;
                            return false;
                        }
                        break;

                    case 3:
                        if(d >= 0) {
                            // Emit the output triple and return to state 0.
                            value = (value << 6) | d;
                            output[op + 2] = (byte)value;
                            output[op + 1] = (byte)(value >> 8);
                            output[op] = (byte)(value >> 16);
                            op += 3;
                            state = 0;
                        } else if(d == EQUALS) {
                            // Emit the last (partial) output tuple;
                            // expect no further data or padding characters.
                            output[op + 1] = (byte)(value >> 2);
                            output[op] = (byte)(value >> 10);
                            op += 2;
                            state = 5;
                        } else if(d != SKIP) {
                            this.state = 6;
                            return false;
                        }
                        break;

                    case 4:
                        if(d == EQUALS) {
                            ++state;
                        } else if(d != SKIP) {
                            this.state = 6;
                            return false;
                        }
                        break;

                    case 5:
                        if(d != SKIP) {
                            this.state = 6;
                            return false;
                        }
                        break;
                }
            }

            if(!finish) {
                // We're out of input, but a future call could provide
                // more.
                this.state = state;
                this.value = value;
                this.op = op;
                return true;
            }

            // Done reading input.  Now figure out where we are left in
            // the state machine and finish up.

            switch(state) {
                case 0:
                    // Output length is a multiple of three.  Fine.
                    break;
                case 1:
                    // Read one extra input byte, which isn't enough to
                    // make another output byte.  Illegal.
                    this.state = 6;
                    return false;
                case 2:
                    // Read two extra input bytes, enough to emit 1 more
                    // output byte.  Fine.
                    output[op++] = (byte)(value >> 4);
                    break;
                case 3:
                    // Read three extra input bytes, enough to emit 2 more
                    // output bytes.  Fine.
                    output[op++] = (byte)(value >> 10);
                    output[op++] = (byte)(value >> 2);
                    break;
                case 4:
                    // Read one padding '=' when we expected 2.  Illegal.
                    this.state = 6;
                    return false;
                case 5:
                    // Read all the padding '='s we expected and no more.
                    // Fine.
                    break;
            }

            this.state = state;
            this.op = op;
            return true;
        }
    }

    //  --------------------------------------------------------
    //  encoding
    //  --------------------------------------------------------

    /**
     * Base64-encode the given data and return a newly allocated
     * String with the result.
     *
     * @param input  the data to encode
     * @param flags  controls certain features of the encoded output.
     *               Passing {@code DEFAULT} results in output that
     *               adheres to RFC 2045.
     */
    public static String encodeToString(byte[] input, int flags) {
        try {
            return Encoding.ASCII.GetString(encode(input, flags));
            //return new String(encode(input, flags), "US-ASCII");
        } catch(Exception e) {
                // US-ASCII is guaranteed to be available.
            throw new Exception("US-ASCII is guaranteed to be available");
        }
    }

    /**
     * Base64-encode the given data and return a newly allocated
     * byte[] with the result.
     *
     * @param input  the data to encode
     * @param flags  controls certain features of the encoded output.
     *               Passing {@code DEFAULT} results in output that
     *               adheres to RFC 2045.
     */
    public static byte[] encode(byte[] input, int flags) {
        return encode(input, 0, input.Length, flags);
    }

    /**
     * Base64-encode the given data and return a newly allocated
     * byte[] with the result.
     *
     * @param input  the data to encode
     * @param offset the position within the input array at which to
     *               start
     * @param len    the number of bytes of input to encode
     * @param flags  controls certain features of the encoded output.
     *               Passing {@code DEFAULT} results in output that
     *               adheres to RFC 2045.
     */
    public static byte[] encode(byte[] input, int offset, int len, int flags) {
        Encoder encoder = new Encoder(flags, null);

        // Compute the exact length of the array we will produce.
        int output_len = len / 3 * 4;

        // Account for the tail of the data and the padding bytes, if any.
        if(encoder.do_padding) {
            if(len % 3 > 0) {
                output_len += 4;
            }
        } else {
            switch(len % 3) {
                case 0: break;
                case 1: output_len += 2; break;
                case 2: output_len += 3; break;
            }
        }

        // Account for the newlines, if any.
        if(encoder.do_newline && len > 0) {
            output_len += (((len - 1) / (3 * Encoder.LINE_GROUPS)) + 1) *
                (encoder.do_cr ? 2 : 1);
        }

        encoder.output = new byte[output_len];
        encoder.process(input, offset, len, true);

        if( encoder.op != output_len) {
            throw new Exception("encoder.op != output_len");
            }

        return encoder.output;
    }

    /* package */
     class Encoder {

        /**
         * Emit a new line every this many output tuples.  Corresponds to
         * a 76-character line length (the maximum allowable according to
         * <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>).
         */
        public static   int LINE_GROUPS = 19;
            public byte[] output;
            public int op;
            /**
             * Lookup table for turning Base64 alphabet positions (6 bits)
             * into output bytes.
             */
            private static   byte[] ENCODE = {
            (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G', (byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N', (byte)'O', (byte)'P',
            (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U', (byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z', (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f',
            (byte)'g', (byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n', (byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u', (byte)'v',
            (byte)'w', (byte)'x', (byte)'y', (byte)'z', (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6', (byte)'7', (byte)'8', (byte)'9', (byte)'+', (byte)'/',
        };

    /**
     * Lookup table for turning Base64 alphabet positions (6 bits)
     * into output bytes.
     */
    private static   byte[] ENCODE_WEBSAFE = {
            (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G', (byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N', (byte)'O', (byte)'P',
            (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U', (byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z', (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f',
            (byte)'g', (byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n', (byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u', (byte)'v',
            (byte)'w', (byte)'x', (byte)'y', (byte)'z', (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6', (byte)'7', (byte)'8', (byte)'9', (byte)'-', (byte)'_',
        };

      private byte[] tail;
    /* package */
    int tailLen;
    private int count;

      public bool do_padding;
      public bool do_newline;
      public bool do_cr;
      private byte[] alphabet;

    public Encoder(int flags, byte[] output) {
        this.output = output;

        do_padding = (flags & NO_PADDING) == 0;
        do_newline = (flags & NO_WRAP) == 0;
        do_cr = (flags & CRLF) != 0;
        alphabet = ((flags & URL_SAFE) == 0) ? ENCODE : ENCODE_WEBSAFE;

        tail = new byte[2];
        tailLen = 0;

        count = do_newline ? LINE_GROUPS : -1;
    }

    /**
     * @return an overestimate for the number of bytes {@code
     * len} bytes could encode to.
     */
    public int maxOutputSize(int len) {
        return len * 8 / 5 + 10;
    }

    public bool process(byte[] input, int offset, int len, bool finish) {
        // Using local variables makes the encoder about 9% faster.
          byte[] alphabet = this.alphabet;
          byte[] output = this.output;
        int op = 0;
        int count = this.count;

        int p = offset;
        len += offset;
        int v = -1;

        // First we need to concatenate the tail of the previous call
        // with any input bytes available now and see if we can empty
        // the tail.

        switch(tailLen) {
            case 0:
                // There was no tail.
                break;

            case 1:
                if(p + 2 <= len) {
                    // A 1-byte tail with at least 2 bytes of
                    // input available now.
                    v = ((tail[0] & 0xff) << 16) |
                        ((input[p++] & 0xff) << 8) |
                        (input[p++] & 0xff);
                    tailLen = 0;
                };
                break;

            case 2:
                if(p + 1 <= len) {
                    // A 2-byte tail with at least 1 byte of input.
                    v = ((tail[0] & 0xff) << 16) |
                        ((tail[1] & 0xff) << 8) |
                        (input[p++] & 0xff);
                    tailLen = 0;
                }
                break;
        }

        if(v != -1) {
            output[op++] = alphabet[(v >> 18) & 0x3f];
            output[op++] = alphabet[(v >> 12) & 0x3f];
            output[op++] = alphabet[(v >> 6) & 0x3f];
            output[op++] = alphabet[v & 0x3f];
            if(--count == 0) {
                if(do_cr) output[op++] = (byte)'\r';
                output[op++] = (byte)'\n';
                count = LINE_GROUPS;
            }
        }

        // At this point either there is no tail, or there are fewer
        // than 3 bytes of input available.

        // The main loop, turning 3 input bytes into 4 output bytes on
        // each iteration.
        while(p + 3 <= len) {
            v = ((input[p] & 0xff) << 16) |
                ((input[p + 1] & 0xff) << 8) |
                (input[p + 2] & 0xff);
            output[op] = alphabet[(v >> 18) & 0x3f];
            output[op + 1] = alphabet[(v >> 12) & 0x3f];
            output[op + 2] = alphabet[(v >> 6) & 0x3f];
            output[op + 3] = alphabet[v & 0x3f];
            p += 3;
            op += 4;
            if(--count == 0) {
                if(do_cr) output[op++] = (byte)'\r';
                output[op++] = (byte)'\n';
                count = LINE_GROUPS;
            }
        }

        if(finish) {
            // Finish up the tail of the input.  Note that we need to
            // consume any bytes in tail before any bytes
            // remaining in input; there should be at most two bytes
            // total.

            if(p - tailLen == len - 1) {
                int t = 0;
                v = ((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 4;
                tailLen -= t;
                output[op++] = alphabet[(v >> 6) & 0x3f];
                output[op++] = alphabet[v & 0x3f];
                if(do_padding) {
                    output[op++] = (byte)'=';
                    output[op++] = (byte)'=';
                }
                if(do_newline) {
                    if(do_cr) output[op++] = (byte)'\r';
                    output[op++] = (byte)'\n';
                }
            } else if(p - tailLen == len - 2) {
                int t = 0;
                v = (((tailLen > 1 ? tail[t++] : input[p++]) & 0xff) << 10) |
                    (((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 2);
                tailLen -= t;
                output[op++] = alphabet[(v >> 12) & 0x3f];
                output[op++] = alphabet[(v >> 6) & 0x3f];
                output[op++] = alphabet[v & 0x3f];
                if(do_padding) {
                    output[op++] = (byte)'=';
                }
                if(do_newline) {
                    if(do_cr) output[op++] = (byte)'\r';
                    output[op++] = (byte)'\n';
                }
            } else if(do_newline && op > 0 && count != LINE_GROUPS) {
                if(do_cr) output[op++] = (byte)'\r';
                output[op++] = (byte)'\n';
            }

        } else {
            // Save the leftovers in tail to be consumed on the next
            // call to encodeInternal.

            if(p == len - 1) {
                tail[tailLen++] = input[p];
            } else if(p == len - 2) {
                tail[tailLen++] = input[p];
                tail[tailLen++] = input[p + 1];
            }
        }

        this.op = op;
        this.count = count;

        return true;
    }
}

}
}